Frequency responsive relay



March 26, 1940.

w. R. KOCH ,559

FREQUENCY RESPONSIVE RELAY Filed April 28. 1937 RFD/0 RECEIVER Zhmentor VVinfield B.Koch

Gttorneg UNITED STATES PATENT OFFICE FREQUENCY BE SPONSIVE RELAY Winfield R. Koch, Merchantville, N. 1., assignor to Radio Corporation of America, a corporation of Delaware Application April 28, 1937, Serial No. 139,34!

6 Claims. (Cl. 250-21) This invention relates to frequency responsive includes a pair of cross connected electron disrelays such as are useful for controlling the charge devices 2| and 22. It will be noted that operation of an electric switch or for producing the double diode device l9 includes a cathode 22 similar results, and has for its principal object and anode 24 which function to detect the high the provision of an improved relay system and frequency control impulses and acathode 25 and 5 method of operation whereby a desired eiiect may anode 25 which function together with a filter be readily produced in response to control imnetwork 21 as a socket power unit for energizing pulses of a predetermined frequency or band of the plate or anode circuits of the various elecfrequencies. tron discharge devices 0)! the circuit. Thus A further object of the invention is the propower is supplied to these various circuits from 10 vision of a radio receiver adapted to have its opthe alternating current terminals 28 through the eration controlled in response to a high frerectifier 25-26 and the filter 21 and heating quency sound such as a clap of the hands, a current is supplied to the various cathodes from snap of the fingers, a hiss or the like. the terminals 28 through a resistor 29. The level As applied to radio receivers, the invention is or volume of the high frequency control im- 15 advantageous in that it permits temporary silencpulses delivered from the amplifier i 8 through ing of the receiver for short periods of time a coupling transformer 30 to the diode 23--24 such as are required for a telephone call, a may be adjusted by means of a resistor 31 conshort conversation or the like. Ashereinafter nected so as to permit control of the steady explained, the invention may be utilized to revoltages applied to the amplifier I1. 20 store operation of the receiver either automat- Connected between the high potential lead 32 ically after a predetermined time interval or and the low potential lead 33 of the filter 21 manually in response to sound of a predeterare an adjustable resistor 34 which is provided mined pitch or frequency. Thus operation of for adjusting the potential of the diode cathode the receiver is readily interrupted and reestab- 23 and an adjustable resistor 35 which is pro- 25 lished by one seated in a chair located 'at a disvided for balancing the operation of the trigger tance from the receiver, such control being availcircuit devices 2i and 22.

able to any one of a number of persons located The devices 21 and 22 are provided with grids at different points in the same room, and with- 36 and 31 which are subjected to a negative out apparatus at the control points. The same potential dependent on the voltage drop promethod of control may obviously be applied to duced in a resistor 38 by the current of the the raising and lowering of a window, the opendiode 23-24, the action of which is delayed by ing and closing of a door and other similar opthe bias potential derived from the resistor 34.

erations. With these connections, a negative potential is The invention will be better understood from applied to the grids 36 and 31 when the peaks of the following description when considered in the rectified control impulses are greater than connection with the accompanying drawing and the bias voltage ap t0 the diode 3 its scope is indicated by the appended claims. The devices 21 and 22 are also provided with Referring to the drawing, cross connected grids 38 and 39 which are sub- 40 Figure l is a wiring diagram of a relay sysjected to potentials dependent on the potential 40 tem which is operable to open and close a switch drops produced in the resistors 40 and 4| by in response to successive sounds or wave trains the outp Currents 0f t es 2| a d 2. It of predetermined frequency, and v will be observed that the grid 38 is connected Figure 2 is a wiring diagram of a control cirto the low potential side of the resistor H through cuit adapted to interrupt operation of a loud a resistor 42 which is shunted y Capacitor 43,

speaker for a predetermined time interval in that the grid 39 is likewise connected to the response to sound of a predetermined pitch. resistor 40 through a resistor 44 which is shunted The system of Fig. 1 includes a microphone y a Capacitor 45 and that the Switch Operating l0 which is interconnected with the Operating coil H is connected in the ou p cuit of the o coil ll of a switch I2 biased to its open position devi 2! and s s u d y a apac t r 46. I 0

by means of a spring l3. Intel-posed between the With these connections, the trigger circuit 20 microphone l0 and switch operating coil H are operates stably with either of the devices 2| and a step-up transformer 14, a band pass filter I5, 22 open and the other closed. Thus, when the concatenated amplifiers l6, l1 and I8, a double device 2| takes load current, the potential of diode detector l9 and a trigger circuit 20 which the grid 39 is reduced to a point where the de- 55 vice 22 is closed and takes no load current and the potential of the grid 38 is consequently raised thus permitting the device 2| to take more current.

The operation of the system will be readily understood if it be assumed that the device 22 is taking load current and a control impulse is picked up by the microphone Ill. Under these conditions, the grids 36 and 31 are temporarily biased to cut-off by the potential produced in the resistor 38 by the rectified control impulses, the load current of the device 22 is interrupted and cessation of the control impulses permits the potentials of the grids 86 and 31 to return to zero. Since the capacitor in series with the grid 36 has not lost all its charge, the potential of the grid 30 is somewhat more negative than that of the grid 38, and the device 2| will take current, the potential of the grid 26 will be reduced to a point where the device 22 takes no load current, and the switch l2 will be operated. A subsequent series of control impulses will permit the device 22 to take load current, interrupt the load current of the device 2| and deenergize the switch operating coil I I in a manner which is apparent from the foregoing explanation.

As previously indicated, the switch may be utilized to short circuit or open circuit a loudspeaker or to control a variety of other operations.

The system of Fig. 2 includes a switch 56 which is biased to its closed position by a spring ii and is provided with an operating coil 52 arranged to be controlled in response to control impulses picked up by a microphone 63 and supplied to it through a channel including a transformer 64, an amplifier 66, a tuned transformer 56 and a diode-triode device 51. Power for operating the control channel may be derived from any suitable source such as a socket power unit 41, cathode heating current being supplied from the terminals 41' or otherwise as desired.

Interconnected with the diode 48-49 are a resistor 68 for applying a negative potential to the control grid 51' of the triode JP-58 and a resistor 66 for automatically controlling the gain of the amplifier 66. In order to ensure quick opening and delayed closing of the switch 60, capacitors 6i and 62 are provided. The horn 63 of the microphone 63 may be so constructed with inlets 64 and 65 that it tends to transmit only sound waves of the control impulse frequency. While the switch is arranged to short-circuit the loud speaker 66 of a loud speaker 61 for a predetermined time interval, it will be apparent that it may be arranged to open circuit this loud speaker or otherwise control various types of devices. For the purpose of reducing the high frequency impulses delivered at the loud speaker 66 an absorption circuit 68 may be connected in shunt to it if desired.

Operation of the system of Fig. 2 is controlled by high frequency impulses which are picked up by the microphone 63 through the acoustically filtered horn 63, amplified by the amplifier 66, detected and amplified by the diode-triode 51 and supplied to the switch operating coil. The length of the time interval during which the switch is maintained open after a train of control impulses is dependent on the sizes of the resistors 69 and and the capacitors 6| and 62 which determine the rate at which the grid potentials return to a non-operating value.

It will be apparent that other trigger circuits than those illustrated may be utilized, thus gaseous electron discharge devices may be used in lieu of high vacuum devices, a push pull relay may be provided, or a suitably controlled mechanical relay of the notching or counting type may be arranged, to actuate the switch. By utilizing acoustic control frequencies higher than those usually present in radio broadcast reception or in the output of the radio receiver, accidental operation of the control circuit is readily avoided.

I claim as my invention:

1. The combination of a sound producing device, means for operating said device to produce sounds in a predetermined frequency range, means for controlling the operation of said device, means operable to energize said control means in response to acoustic impulses of a frequency above said predetermined range, and means including a pair of electron discharge devices operable to energize said control means in response to acoustic impulses of a frequency above said predetermined range and to deenergize said control means in response to a subsequent train of said impulses.

2. The combination of a device to be operated, means for controlling the operation of said device, means operable to energize said control means in response to acoustic impulses in a frequency range adjacent to the upper limit of audibility, means including a trigger circuit operable to energize said control means in response to acoustic impulses in a frequency range adjacent to the upper limit of audibility, and to deenergize said control means in response to a subsequent train of said impulses, and means operable to delay the operation of said trigger circuit.

3. Frequency responsive relay means for con trolling radio receiving apparatus and the like comprising, in combination, a microphone device responsive to audio frequency signals in the upper range of audibility, an amplifier for said microphone device provided with sensitivity control means whereby the sound level of the response of said device is determined, means for limiting the response of said amplifier to acoustical impulses at frequencies higher than those normally present in radio broadcast reception or in the output of a radio receiving system whereby accidental operation of the frequency responsive relay means is prevented, a signal rectifier device coupled to said amplifier to provide a controlling potential responsive to acoustical impulses transmitted to said amplifier, means providing a controllable delay in the operation of said rectifier, a relay device having contacts for controlling the operation of a radio receiving system and having an operating winding, and an amplifier having a control circuit connected with said rectifier device and an output circuit connected with said operating winding, whereby said operation is controllable in response to ascoustical impulses above the normal range of audio frequency signal output from said receiving systom.

4. Frequency responsive relay means for controlling radio receiving apparatus and the like comprising, in combination, a microphone device responsive to audio frequency signals in the upper range of audibility, an amplifier for said microphone device provided with sensitivity control means whereby the sound level of the response of said device is determined, means for limiting the response of said amplifier to acoustical impulses at frequencies higher than those normally present in radio broadcast reception or in the output of a radio receiving system whereby 8,104,850 accidental operation of the frequency responsive relay means is prevented, a signal rectifier device connected to said amplifier. a trigger amplifier controlled by the output from said rectifier comprising a pair of amplifier tubes, and a relay device having control contacts and an operating winding in circuitjwith one of said trigger amplifiers.

5. The combination with sound producing means having a predetermined frequency range of operation, of a frequency responsive relay means for modifying the acoustical output of said sound producing means, while being immune to operation in response to said acoustical output, said relay means comprising an audio frequency amplifier, means for applying to said amplifier audio frequency signals in a frequency range above the normal frequency range of said sound producing means and in a relatively high audio frequency range adjacent to the normal upper limit of audibility, a rectifier coupled to said amplifier to receive the high audio frequency output therefrom and to convert the same into a controlling potential, means responsive to said potential for modifying the operation of said sound producing means, and means for modifying the application of said control potential to said last named means whereby a predetermined operating characteristic is obtained for said last named means.

6. Frequency responsive relay means for silencing a radio receiver having a sound producing device comprising silencing means for said sound producing device responsive to a controllng current, an amplifier for supplying said current to said silencing means, and means for applying a controlling potential to said amplifier in response to acoustical impulses in an audio frequency range above the frequency range of signals applied to said sound producing device through said receiver and of a predetermined amplitude.

Y WINFIELD R. KOCH. 

